Machine and method for covering balls



Oct. 27, 1942. A. c. BOWERS- 5 MACHINE AND METHOD FOR COVERING BKLLS Fi1ed Jan. 25, 1939 2 Sheets Sheet 1 Oct. 27, 1942. A. c. BOWERS 2,300,095

MACHINE AND METHOD FQR COVERING BALLS Filed Jan. 25, 1939- 2 Sheets-Sheet 2 Patented Oct. 27, 1942 MACHINE AND METHOD FOR COVERING BALLS Archibald C. Bowers, Greensbu'rg, Pa., assignor to Pennsylvania Rubber Company, a corporation of Pennsylvania Application January 25, 1939, Serial No. 252,775

6 Claims.

This invention relates to th covering of tennis balls, and consists in improvements both in method, and in the machine in whose operation the method is accomplished.

In the accompanying drawings Fig. I is a view in perspective of one of two duplicate two-part press members that together make up the press of the invention. This member is here shown in' open position. Fig. II is a view in plan of one of two duplicate blanks of material that, applied to a ball, together constitute the cover; Fig. III is a view in medial and transverse section of one of the press members in open position, and with a blank in position within it; and in this figure an uncovered ball is shown in elevation and in diagrammatic association with the open illustrating diagrammatically the closing of the.

press in the ball-covering operation. Fig. VIII is a view in perspective of the covered balls v The tennis ball of today is a highly refined product, and in form, dimensions, and structure is minutely standardized; It consists of a spherical shell of vulcanized rubber enclosing a segregated body of air (with which other gas may be mingled) under a pressure somewhat exceeding atmospheric, and a cover of woolen fabric of quality and character known in th industry as felt or felt cloth, cemented upon its outer surface. cover to the rubber ball that this invention has to do.

The cover is formed from cloth woven in a plane; that is to say, in sheet-like web. From the web of cloth two-identical blanks are cut, and

these are applied to and shape upon the ball, to meet edge to edge and to form together a continuous cover. The two identical blanks are of Cassinian outline with symmetrical, approximately semi-circular ends connected by a narrower, reversely curved waist. If, as is usual, the cloth be woven, the blank is out on the bias, so that the, threads of the warp and the woof extend obliquely to the major axis of the blank.

'Such a blank is illustrated in Fig. II of the draw ings, and in this figure the warp andwoof are diagrammatically indicated in dotted lines. Two such blanks are applied to th ball, each with its major axis on a great circle or th sphere of the It is with the application of the felt I ball, the two great circles lying in planes per- 55 pendicular to one another, and each blank extending with its major axis in continuity with the minor axis (that is to say, the axis perpendicular to the major axis, mid-way in the length thereof) of the other.

In the practic that up to this time has prevailed, the two blanks are successively applied, and are shaped by hand upon th ball. Both the ball and the inner face and the edges of the blank (for the rather firm and bulky web of felt cloth has substantial thickness) are preliminarily coated with a colloidal suspension of still unvulcanized rubber. (The preparation is known as rubber cement.) The carrier evaporates, and a tacky film remains. The first of the two blanks is wrapped tangentially upon the ball along its major axis, and its flaring sides are then pressed down upon and shaped to'the spherical surface,

until, adhesion is complete to the edges of the blank. The second blank is then applied. It is laid tangentially upon the ball, as the first blank was laid, and its flaring sides are then shaped upon the spherical surface, with care that its edges shall abut upon the edges of the previously laid first blank. Consequent upon the mode of application described, the web of fabric of the v first blank, unrestrained at the edge, expands somewhat under the hand of the workman on lines perpendicular to the edge; the web of fabric of the second blank, however, confined by edge abutment upon the first, does not so expand. The hand-applied cover, therefore, is characterized by a consistent, localized disparity in the density of th substance of the cover. In an article so highly standardized, even such small irregularities are undesirable; and it is a feature of the method of my invention that the irregularity that has been described of the hand-applied cover is eliminated.

The machine of the invention is a press made up of two duplicate press members. Each press member is a two-part structure, the two parts hinged together. It will be understood that suitable mechanical means (not shown) will ordinarily be provided, to support the two press members in proper space relation, to move them relatively to one another, and to open and close them, and in so doing to accomplish the method hereinafter described.

Referring, first, to Figs. I and V, each press member consists of the two block I and 2 (la, 2a), hinged at 3 (3a), and capable of swinging between the open position of Fig. I and the closed position of Fig. V. The two blocks are formed with face H and I2 (cf. Fig. III) of spherical concavity, the spherical curvature being that of th covered ball; the peripheral outline of each concave face is exactly that or half or a cover part (Fig. II) when shaped and compressed upon the ball; th line or division of the two halves is that or the minor axis (defined above) or the Cassinian outline or the cover part;

and the axis of the hinge 3 extends in the equatorial plane in which, when the press is closed, that minbr axis lies, and is substantially tangent to the covered ball within the closed press. At the peripheries the faces ll andslz of the blocks are provided with thin, discontinuous rim I3, 23,

for retaining the applied cover without slipping.

The two press members are arranged with the blank in position axes of their hingeslying in parallel planes, and

both are centered in a line perpendicular to the two planes. and the two axes extend in directions.

at right angles to one another. The two press members are relatively movable in the line of the perpendicular just defined.

Two blanks, C, C previously coated over one face and over all their edges with coatings c of rubber cement, are applied to and shaped within the joint concavities presented by the two open press members, as indicated in Fig. III. The exposed face of the so seated blank is the cementcoatcclface.

When the two press members have so been provided with cover blanks, while they still are open,

and while they still are in separated relative positions, a naked, that is to say, uncovered, ball B (Fig. 111), upon whose surface a coating of rubber cement has been spread, is introduced between them, and may, conveniently, rest within it will be realized that in such relative movement there can be no appreciable trapping of air. Re-

ferring to Fig. VII it will be perceived. that, as the two press members close upon the ball, the cement-faced edges of the cover blanks come together along symmetrical lines of approach, so that the substance of the assembled cover is of uniform density on the two sides of the seam. In the shaping of the blank to the concavity of the mold there-is a bending of the obliquely lying strands to are shape, and there is some relative movement of the woven strands. These minute changes within the substance of the fabric are uniform throughout the extent of the blank. Only at the waist of the Cassinian outline and to one side and the other of the longitudinal axis does 'the'fabrlc continue without such interior displacement of the strands: but

' when, eventually, the press member closes, the

same changes that have taken place elsewhere take place in those regions also. The operation of coating a succession of balls asodoeo proximation to ideal standards, and uniformity between ball and ball is greater.

The discontinuous rims l3 and 23 of the press member consist of successions of short portions of rim separated by rimless intervals. As between the two press members the rim portions are so arranged that the cement-faced edges of the two blanks come discontinuously into immediate contact, so that within the press a firm though discontinuous seam is formed, as is indicated-in Figs. V and VI by thebroken heavy the seams. Such a step, however, I do not now regard as a necessary one. My tests have indicated that the continuity gained in the vulcanizing press is complete.

' I claim as my invention:

1. The method herein described of applying to a naked ball a fabric cover that is formed of two complementary'planar blanks of Cassinian outline, which method consists in shaping the ends of the two blanks to spherical shape, and simultaneously closing the so-shaped blanks upon the sphere of the ball and in so doing bringing the edges of the blanks to abutment as. they come to place on the ball.

2. The method herein described of applying to a naked ball aiabric cover that is formed of two complementary planar blanks of Cassinian outline, which method consists in shaping the two blanks simultaneously to spherical shape upon the surface of the ball with discontinuous abutment of the two blanks at their edges as they come simultaneously to position, and subsequently making continuous the edge-to-edge abutment of the applied blanks.

' blocks extending when the blocks are in closed in the manner and by the operation of the ma position substantially in tangency to the covered tions atright anglesto one another, the two members being relatively movable in the direction of the line defined above in which the hinges are centered.

6. A machine for applying to a naked tennis ball two complementary blanks of cover fabric of Cassinian outline, the machine including two press members as defined in claim 3, the press members being provided at the edges of their concave faces with discontinuous blank retaining rims, the two press members being assembled with their hinge axes disposed in parallel planes, the hinges of the two members being centered in a single line perpendicular to the two planes, and the axes of the two hinges extending in directions at right angles to one another, the two members being relatively movable in the direction of the line defined above in which the hinges are centered, the discontinuous rims of the two press members being so disposed that as the blocks of the two members close the edges of two block-borne cover blanks come to immediate abutment over discontinuous areas 10 in the extent of the blank edges,

ARCHIBALD C. BOWERS. 

